The present invention relates to a method in which water for preventing the concentration of processing solution in a processing tank from being increased due to evaporation and a replenisher for avoiding a lowering of the effectiveness of the processing solution are added to the processing tank of a photographic processing apparatus. Before the processing tank is replenished with a replenisher, the processing tank is replenished with water by an amount corresponding to the amount of water evaporated therefrom until the liquid surface level reaches the original liquid surface level i.e. replacing evaporated water, and then, the processing tank is replenished with replenisher. Thereafter, the processing solution is discharged by an amount equal to the amount of replenisher added in order to return the liquid surface level to the original liquid surface level. Thus, the performance of the processing solution can be restored while the concentration of the processing solution is kept constant.